FYI, we noticed the following commit: https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git x86/uaccess commit 69ba758fea06cfb812c4f8aed268e7220a18c5ec ("x86/uaccess: OOPS or warn on a fault with KERNEL_DS and !pagefault_disabled()") on test machine: vm-kbuild-1G: 2 threads qemu-system-x86_64 -enable-kvm -cpu Haswell,+smep,+smap with 1G memory caused below changes: +----------------+------------+------------+ | | 912b531949 | 69ba758fea | +----------------+------------+------------+ | boot_successes | 2 | 0 | +----------------+------------+------------+ [ 0.583483] apic 0 pin 23 not connected [ 0.584358] ..TIMER: vector=0x30 apic1=0 pin1=2 apic2=-1 pin2=-1 [ 0.586124] TSC deadline timer enabled [ 0.598914] BUG: uaccess fault at 0xffff880036b18000 with KERNEL_DS [ 0.600685] BUG: unable to handle kernel paging request at ffff880036b18000 [ 0.602690] IP: [<ffffffff811546fa>] copy_mount_options+0x124/0x19c [ 0.604489] PGD 18b6067 PUD 18b7067 PMD 3874c067 PTE 8000000036b18060 [ 0.606397] Oops: 0000 [#1] DEBUG_PAGEALLOC [ 0.624298] Modules linked in: [ 0.625183] CPU: 0 PID: 8 Comm: kdevtmpfs Not tainted 4.7.0-rc1-00129-g69ba758 #1 [ 0.627233] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Debian-1.8.2-1 04/01/2014 [ 0.635177] task: ffff880036b00540 ti: ffff880036b14000 task.ti: ffff880036b14000 [ 0.637276] task.addr_limit: 0xffffffffffffffff [ 0.638661] RIP: 0010:[<ffffffff811546fa>] [<ffffffff811546fa>] copy_mount_options+0x124/0x19c [ 0.641069] RSP: 0000:ffff880036b17df0 EFLAGS: 00010206 [ 0.642538] RAX: 0000000000000000 RBX: 0000000000000e7e RCX: 0000000000000000 [ 0.659516] RDX: ffff880036a85182 RSI: 0000000000000000 RDI: ffffffff816bc6b8 [ 0.661378] RBP: ffff880036b17e30 R08: 0000000000001000 R09: 00003ffffffff000 [ 0.663340] R10: ffff880036b17cc8 R11: 0000000000000001 R12: ffff880036b18000 [ 0.665285] R13: 0000000000001000 R14: 0000000036b17e01 R15: ffff880036a85000 [ 0.678571] FS: 0000000000000000(0000) GS:ffffffff8162d000(0000) knlGS:0000000000000000 [ 0.680849] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 0.682434] CR2: ffff880036b18000 CR3: 000000000160c000 CR4: 00000000000406b0 [ 0.684448] Stack: [ 0.685033] 0000000000000000 ffff880036b18e7e ffffffffffffffff ffffffff8152b089 [ 0.687205] ffff880036afda40 ffff880036afd000 ffff880036b17e7e 0000000000008000 [ 0.698344] ffff880036b17e68 ffffffff811554fd ffff880036ab7ee4 ffff880036ab7ee4 [ 0.705908] Call Trace: [ 0.706581] [<ffffffff811554fd>] SyS_mount+0x8f/0xf6 [ 0.707798] [<ffffffff81263850>] ? handle_create+0x207/0x207 [ 0.714078] [<ffffffff812638ae>] devtmpfsd+0x5e/0x152 [ 0.715360] [<ffffffff81263850>] ? handle_create+0x207/0x207 [ 0.716861] [<ffffffff810590c8>] kthread+0xee/0xf6 [ 0.718131] [<ffffffff81355f7f>] ret_from_fork+0x1f/0x40 [ 0.723098] [<ffffffff81058fda>] ? kthread_worker_fn+0x1d7/0x1d7 [ 0.737345] Code: ff 41 83 f6 01 41 0f b6 f6 ba 01 00 00 00 48 c7 c7 b8 c6 6b 81 e8 d0 a6 f5 ff 45 84 f6 74 34 4c 89 fa 31 c9 eb 28 0f 1f 00 89 c8 <41> 8a 34 24 0f 1f 00 85 c0 74 0b 89 d9 31 c0 48 89 d7 f3 aa eb [ 0.743648] RIP [<ffffffff811546fa>] copy_mount_options+0x124/0x19c [ 0.745401] RSP <ffff880036b17df0> [ 0.746394] CR2: ffff880036b18000 [ 0.747273] ---[ end trace 5b586953c01d161b ]--- [ 0.754807] Kernel panic - not syncing: Fatal exception FYI, raw QEMU command line is: qemu-system-x86_64 -enable-kvm -cpu Haswell,+smep,+smap -kernel /pkg/linux/x86_64-randconfig-s4-06040525/gcc-6/69ba758fea06cfb812c4f8aed268e7220a18c5ec/vmlinuz-4.7.0-rc1-00129-g69ba758 -append 'root=/dev/ram0 user=lkp job=/lkp/scheduled/vm-kbuild-1G-2/bisect_boot-1-debian-x86_64-2015-02-07.cgz-x86_64-randconfig-s4-06040525-69ba758fea06cfb812c4f8aed268e7220a18c5ec-20160604-38251-olqjqa-0.yaml ARCH=x86_64 kconfig=x86_64-randconfig-s4-06040525 branch=linux-devel/devel-hourly-2016060401 commit=69ba758fea06cfb812c4f8aed268e7220a18c5ec BOOT_IMAGE=/pkg/linux/x86_64-randconfig-s4-06040525/gcc-6/69ba758fea06cfb812c4f8aed268e7220a18c5ec/vmlinuz-4.7.0-rc1-00129-g69ba758 max_uptime=600 RESULT_ROOT=/result/boot/1/vm-kbuild-1G/debian-x86_64-2015-02-07.cgz/x86_64-randconfig-s4-06040525/gcc-6/69ba758fea06cfb812c4f8aed268e7220a18c5ec/0 LKP_SERVER=inn earlyprintk=ttyS0,115200 systemd.log_level=err debug apic=debug sysrq_always_enabled rcupdate.rcu_cpu_stall_timeout=100 panic=-1 softlockup_panic=1 nmi_watchdog=panic oops=panic load_ramdisk=2 prompt_ramdisk=0 console=ttyS0,115200 console=tty0 vga=normal rw ip=::::vm-kbuild-1G-2::dhcp' -initrd /fs/sdd1/initrd-vm-kbuild-1G-2 -m 1024 -smp 2 -device e1000,netdev=net0 -netdev user,id=net0,hostfwd=tcp::23001-:22 -boot order=nc -no-reboot -watchdog i6300esb -rtc base=localtime -device virtio-scsi-pci,id=scsi0 -drive file=/fs/sdd1/disk0-vm-kbuild-1G-2,if=none,id=hd0,media=disk,aio=native,cache=none -device scsi-hd,bus=scsi0.0,drive=hd0,scsi-id=1,lun=0 -drive file=/fs/sdd1/disk1-vm-kbuild-1G-2,if=none,id=hd1,media=disk,aio=native,cache=none -device scsi-hd,bus=scsi0.0,drive=hd1,scsi-id=1,lun=1 -drive file=/fs/sdd1/disk2-vm-kbuild-1G-2,if=none,id=hd2,media=disk,aio=native,cache=none -device scsi-hd,bus=scsi0.0,drive=hd2,scsi-id=1,lun=2 -drive file=/fs/sdd1/disk3-vm-kbuild-1G-2,if=none,id=hd3,media=disk,aio=native,cache=none -device scsi-hd,bus=scsi0.0,drive=hd3,scsi-id=1,lun=3 -drive file=/fs/sdd1/disk4-vm-kbuild-1G-2,if=none,id=hd4,media=disk,aio=native,cache=none -device scsi-hd,bus=scsi0.0,drive=hd4,scsi-id=1,lun=4 -pidfile /dev/shm/kboot/pid-vm-kbuild-1G-2 -serial file:/dev/shm/kboot/serial-vm-kbuild-1G-2 -daemonize -display none -monitor null Thanks, Kernel Test Robot